In the related art, when a session during communication is switched from a cellular terminal with a narrow wireless band to a WiMAX terminal with a wide wireless band, that is, when a handover is performed between terminals, the terminal subjected to the handover performs negotiation with a correspondent node according to a session protocol, such as an SIP. During this process, a new session using a new IP address is established.
The change of the IP address causes disconnection of the session during communication, as it is. However, a technique has been developed which provides a session layer such that an application does not recognize a change in IP address.
In recent years, a telecommunications standards organization has proposed the architecture of a PAN (Personal Area Network) including a mobile telephone with a subscriber identifier to a mobile network and a plurality of adjacent terminals that are connected to each other by a local area communication technique. The technique for performing a handover between the terminals is also applied to the PAN.
The current mobile telephone can use infrared communication or USB for connection to other adjacent terminals. Meanwhile, for example, WLAN, Bluetooth, or ZigBee is used for local area wireless connection to, for example, a personal computer.
In the Mobile IP technique defined by the IETF, a terminal has a home address HoA and a care-of address CoA, and is managed by a corresponding home agent HA. A Downlink packet transmitted to the terminal is intercepted by the home agent HA, encapsulated with the care-of address CoA, and then transferred to the terminal. In addition, an Uplink packet transmitted from the terminal is transmitted by reverse tunneling for encapsulation up to the HA or route optimization between the terminal and a CN, which is a correspondent node. The Mobile IP is classified into various protocols according to the CoA. For example, in IPv6, terminals have different CoAs, and in IPv4, the CoA is defined as a Co-located CoA.
For example, the following technique has been proposed. In a first data path between a home agent (HA) and a first foreign agent (FA), when a reservation for data flow between the HA and a wireless terminal is established and the wireless terminal is associated with a second FA, a second data path is established between the first FA and the second FA in order to support the quality of service, and data flow is transferred through the first and second data paths in order to maintain the quality of service. A wireless communication network includes a first downstream and reverse tunnel that connects the HA and the first FA, and a reservation for maintaining the quality of service is established for each tunnel. A second downstream and reverse tunnel connects the HA and the second FA. When a wireless terminal is handed over from the first FA to the second FA, some or all of the resources reserved by the first tunnel are shared by the second tunnel, thereby maintaining the quality of service in the wireless communication network (for example, refer to Patent Document 1).
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-173274